A headlight lens of that type is e.g. known from U.S. Pat. No. 3,708,221, WO 02/31543 A1, WO 03/074251 A1 and DE 100 52 653 A1. Further types of vehicle headlights are known e.g. DE 101 18 687 A1 and DE 198 29 586 A1.
DE 203 20 546 U1 discloses a lens blank-moulded on both sides and having a curved surface, a planar surface and a retention edge integrally moulded on the lens edge, wherein a supporting edge of a thickness of at least 0.2 mm and projecting with respect to the planar surface is integrally formed on the retention edge. Herein, the supporting edge is integrally formed on the outer circumference of the headlight lens. A further headlight lens having a supporting edge is disclosed e.g. by DE 10 2004 048 500 A1.
DE 20 2004 005 936 U1 discloses a lens for illuminating purposes, in particular a lens for a headlight for mapping or imaging light emitted from a light source and reflected by a reflector for generating a predetermined illumination pattern, said lens having two surfaces opposing each other, wherein areas of different optical dispersion effects are provided on at least a first surface.
EP 0 969 246 A2 discloses an over-dimensioned lens, wherein the lens grinding and the corresponding projection plane and projection parameter of the reflector mirror are dimensioned such with respect to the lens that only an interior partial area of the lens is used directly. The over-dimensioned edge area merely serves for an optical magnification of the headlight design.
With respect to their optical properties or their photometric standards, headlight lenses are subject to narrow criteria of design. This particularly applies to a light and dark borderline 75, as has been represented, by way of example, in a diagram 70 and a photo 71 in FIG. 9. Herein, the gradient G of the light and dark borderline 75 and the glare value HV of the vehicle headlight into which the headlight lens is installed are important photometric standard values.
It is the object of the invention to reduce the costs in manufacturing a headlight lens for a vehicle headlight, in particular for a motor vehicle headlight, without exceeding photometric standard values.